Abstract Detail

Bryology and Lichenology

Ranathunge, Chathurani [1], Butler, Julia [2], Contreras, Juan [2], Roles, Angela J. [2], McDaniel, Stuart [3].

Reconstructing the evolutionary history of the boreal moss genus Aulacomnium.

A central problem in evolutionary biology is to identify the processes that lead to the evolution of reproductive isolation, thereby generating biodiversity. The most widely accepted model of speciation involves a period of allopatry, during which gene flow is stopped by a geographic barrier. This mechanism may not work in species such as bryophytes where spore dispersal is widespread, meaning even distant populations may exchange genes. Here we examined the genetic diversity in Alaskan populations of members of the moss genus Aulacomnium, a critical component of rapidly changing boreal ecosystems and a host of N-fixing microbes. In Alaska, Aulacomnium palustre grows from temperate forests to arctic tundra while less frequent A. turgidum and A. acuminatum often occur in intermixed patches with A. palustre. Phenotypically, A. palustre and A. turgidum are distinct while A. acuminatum is an intermediate between the other two species. The close phenotypic similarity coupled with the overlapping geographic distributions in this system indicate potential gene flow among these three species. We tested this hypothesis by studying the evolutionary history and genetic diversity of these three closely related species with 199 individuals sampled from Anchorage to Toolik Lake, Alaska. We used double digest restriction site associated DNA sequencing (ddRADseq) to identify single nucleotide polymorphisms (SNPs) among the individuals. With 3022 SNPs identified from ddRADseq, we assessed infraspecific genetic structure and phylogenetic relationships among the studied species based on maximum-likelihood approaches. Our data suggest that A. palustre and A. turgidum are phylogenetically distinct, and genetically diverse, but their relationship to A. acuminatum remains ambiguous. Our study provides important insights into the evolutionary history of a system that could prove useful for ongoing work in rapidly changing ecosystems. In particular, evidence consistent with ongoing gene flow among these closely related species could make Aulacomnium an ideal system to identify specific genetic variants associated with microbiome assembly and function.

1 - University of Florida, Biology, 876 Newell Dr, Gainesville, FL , 32611, USA
2 - Oberlin College and Conservatory, Biology
3 - Biology Department, University Of Florida, Gainesville, FL, 32611, United States

Keywords:
Aulacomniaceae
Aulacomnium palustre
Aulacomnium turgidum
Aulacomnium acuminatum
genetic diversity
RADseq
speciation.

Presentation Type: Oral Paper
Session: BRY1, Bryology
Location: Tucson G/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 8:45 AM
Number: BRY1002
Abstract ID:843
Candidate for Awards:None